Contamination free extrusion mill



Nov. 28, 1.961

Filed July 14, 1959 E. N. MEAKIN CONTAMINATION FREE EXTRUSION MILL 2Sheets-Sheet l Nov. 28, 1961 E. N. MEAKIN 3,910,150

CONTAMINATION FREE EXTRUSION MILL Filed July 14, 1959 2 Sheets-Sheet 2INVENTOR. EDGAR N. MEA/(IN mfg/0% H/s Arron/VHS l 3,010,150 CNTAMINATEONFREE EXTRUSION MEL Edgar N. Meakin, 372 Roblar Ave., Hillsborough,Calif. Filed July 14, 1959, Ser. No. 827,059 6 Claims. (Ci. 13-12) Myinvention relates to extrusion apparatus and more particularly to a millfor the pelleting of extrudable material.

ln the pelleting of material, where such material is of a finely dividednature, lubrication problems often arise, due to the fact thatlubrication seals are not wholly immune to penetration by such nelydivided material, and ultimately, servicing of the machine becomesnecessary.

Further, cer-tain materials, asa pelleted product, must retain theirinitial purity, and contamination by oil from earings in the machinecannot be tolerated.

Conventional pellet mill design offers no solution to these problems.

Among the objects of my invention are:

(l) To provide a novel and improved extrusionmill adapted for use inpelleting of finely divided extrudable material;

(2) To provide a novel and improved extrusion mill which will minimizethe probability of interference with lubrication through leakage of theextrudable material past the lubrication seals;

(3) To provide a novel and improved extrusion mill which will minimizecontamination of the extrudable material through leakage of lubricatingoil from the bearings of such machine.

Additional objects of my invention will -be brought out in the followingdescription of a preferred embodiment of the same, taken in conjunctionwith the accompanying drawings, wherein; v

FIG. l is a vertical View in section through a machine embodying thepresent invention;

FIG. 2 is a front elevational view of the same, partly broken away toexpose a detail therefor.

Referring to the drawings for details of my invention in its preferredform, the extrusion mill depicted therein comprises a housing 1 having afront wall 3 and a rear wall 5, each of which walls has a shaft openingtherethrough, with the opening in the front wall of substantiallygreater diameter than that of the rear wall.

Mounted within the shaft opening of the rear wall is a bearing assembly11 to support the tail end of a drive shaft 13 while to the front wall,is affixed a face plate 15 having a forwardly directed peripheral rim 17and a rearwardly directed flange 19 extending into the shaft opening ofthe front wall, in which to mount a front bearing assembly 21 to supportthe front end of such drive shaft, such bearing assembly including aseal 23.

Intermediate the bearing assemblies 11 and 21 and mounted on the driveshaft 13 is a drive gear 25 in engagement with a drive pinion 27 carriedby a shaft 29 supported in bearing assemblies 31, 33 carried by thefront and rear walls respectively.

The drive shaft 13 is of hollow` construction providing an axial passage37 therethrough, the shaft 4itself being of an increasing outsidediameter toward its front end, where it terminates in an outside flange39 and the passage ends in a conical discharge outlet 41.

Removably aflixed to the front end of the drive shaft 13 by a suitableconventional clamping ring 45, is a ring die @i6 which will rotate withthe drive shaft. This ring die is preferably formed at its free end in afrontal rib 47 having a groove 49 along the base of such rib.

A chamber type door 51 lmounted on hinges 53 along a front vertical edgeof the machine housing, is adapted tent in its closed position, toenclose the ring die 46 and engage the free edge of said die to completea die chamber 55, and at the same time mesh with the flanged face plateto provide for an extruded product chamber 57 about the die.

The door is basically cylindrical in shape and includes a front circularwall 59 having an insert 61 eccentrically located therein and bounded bya cylindrical flange 63, said insert having a shaft opening 6-5concentric with the cylindrical liange 63 but eccentric to the axis ofthe die chamber. At its lower end, the door has a discharge opening 67Ithrough which is discharged the extruded product of the machine.

Along the `circle of contact with the free edge of the die, the doorinsert carries a spring pressured ring seal 7l in a groove provided forsuch seal.

The cylindrical ange on the front wall of the door constitutes means forsupporting a bearing assembly 77 externally of the machine, in which torotatably mount a shaft 79 which extends through the opening 65 in thedoor and into the die chamber, where it mounts an extrusion element S1in the form of a roll.

The roll shaft bearing assembly 77 includes an outer bearing shell 83adapted to smoothly lit within the cylindrical flange 63, said outershell being provided with an intermediate outside flange 85 adapted toengage the exposed end of the cylindrical flange where, by means of aclamping ring 8'7, the bearing assembly may be securely retained inposition. Longitudinally spaced bearings 91, 93 within the outer shell83 support the roll shaft in proper aligned position.

Adjacent the surface of the door, the roll shaft is `formed with alaterally extending flange 97. Between the peripheral edge of thisllange and the outer shell 83 of the bearing assembly, -is a leakseal'99 while mounted in a groove in the face of the liange, is a springpressured ring seal 101 maintained in frictional contact with the doorinsert,

An end cap 105 bolted `to the outer shell, permits, in conjunction withthe leak seal 99, of the retention of lubricant in the bearing assembly77.

The roll is preferably keyed or otherwise affixed against rotation onthe shaft, and is adjustable into and out of extrusion Contact with thedie, b-y making the outer shell 83 of the bearing assembly, of graduallyvarying thickness, whereby the roll shaft will be eccentrically disposedwith respect to the outside diameter of the outer shell. Upon looseningthe clamping ring 87, the entire bearing assembly 77 can then beangularly rotated sufficiently to adjust the roll with respect to thedie, and when properly adjusted, its position may be lixed by againtightening the clamping ring.

To relieve the strain placed on the door hinges' by reason of thecombined weight of the door and mounted bearing assembly and roll shaft,a peripheral flange 109 on the door adapted to abut the rim 17 of theface plate, permits of the door, in its closed position, to be bolted tothe front wall of the machine housing.

Material to be extruded, is fed into the die chamber through the hollowdrive shaft 13 by means of a feed screw 111 lying within the hollowshaft and protruding beyond the tail end thereof where it terminates ina stub shaft 113 for coupling the screw-to a source of drive power. Ascrew housing 115 for the exposed end of the feed screw, includes -afeed hopper 117, and enters at one end, the drive shaft passage to guardagainst loss of material being fed from the screw housing. A beatingassembly 119 for the drive end of the screw is aliixed to a wall of thescrew housing.

Material fedinto the die chamber, will accordingly be 3 extruded throughthe ring die and emerge therefrom as strings of extruded material whichmay be severed into pellets by a knife assembly 123 adjustably mountedin the cylindrical wall of the door, with the knife component 12S heldin substantial contac-t with the discharge side of the die.

The material to be extruded is loaded into the hopper 117 of the screwhousing and fed by the rotating screw 111 through the hollow drive shaft13 from which it is discharged into the die chamber 55 and then extrudedthrough the die from which the extruded material is severed into pelletsand discharged through the lower opening 67 in the door.

Movement of the extrudable material into the die chamber will cause someof the material to pile up against the door and more specifically theinsert 61 in the lfront wall f the door and around the exposed end ofthe roll shaft 79, but escape of such material from the die chamber atthis point is discouraged by the ring seal 101 in the flange of the rollshaft.

In like manner, pellet dust or other fines created in the extrusionchamber S7 are blocked from filtering back into the die chamber 55 bythe similar ring seal 71 in the engaging side of the front door insert.

Access of such dust or fines from the extrusion chamber to the region offront supporting bearing assembly 21 for the drive shaft, is avoided bythe provision of a blocking wall assembly 131 including a blocking Wall133 affixed to the flange 39 at the front end. of the drive shaft 13 andextending substantially to the inner peripheral wall surface of theextrusion chamber 57. Adjacent the front surface of this blocking walland axed to the inner peripheral surface of the extrusion chamber, is aring or rib 137 which will block movement of dust or fines by the freeedge of the blocking wa-ll along the inner surface of vthe extrusionchamber. To discourage escape of dust `or small particles by Way of ltheextremely narrow space between the blocking wall 133 and the rib 137, ashroud y139 of ring shape is affixed to the blocking wall and inoverhanging relationship to the rib.

The .aforementioned seal means 101, 71 and 131 serve to precludecontamination of the lubricating oil in the bearings of the machine bythe material under extrusion.

Contamination of the material itself by oil employed in lubricating thebearings of the machine, is precluded primarily by the design of themachine which enables the bearing assemblies to be located outside ofthe die chamber and extrusion chamber, whereby, even should one of thelubrication seals 23 or 99 go bad, leakage of oil from the associatedbearing assemblies is not likely to result in such oil 'finding its wayinto .the die chamber or into the extrusion chamber to contaminate thematerial.

To further minimize probable contamination of the material by suchlubricating oil in the event of a leaky seal, escape openings areprovided to permit such oil to discharge from the machine and notaccumulate therein. One or more such escape openings 143 are located inthe door at the junction of the cylindrical. flange 63 with the frontwall thereof, while a similar discharge opening or openings 145 areprovided through the cooperating rim portions of the face plate 1S andthe door at the lowerrnost point thereof.

While only one extrusion roll is provided for in the above embodiment ofthe invention, as many may be incorporated `as the door can accommodate.

From the foregoing, it will be apparent that the extrusion Vmill of thepresent invention will fulfill all the objects attributable there-to andwhile I have disclosed my invention in its preferred form, it will beapparent that the same is subject to change and modification withoutdeparting from the underlying principles involved. I accordingly do notdesire to be limited in my protection to the specific detailsillustrated and described except as may be necessitated by the appendedclaimsA g I claim:

l. An extrusion mill comprising a housing having front and rear walls, ahollow shaft rotatably supported by said walls and extending beyond saidfront wall, a ring die carried on an end of said hollow shaft beyond andadjacent said front Wall, a door hinged to said housing and adapted toenclose said die and engage the edge thereof to complete a die chamber,extrusion means within said die chamber carried by said door and adaptedfor withdrawal with opening of said door, and means for feedingextrudable material through said hollow shaft into said die chamber forextrusion through said die.

2. An extrusion mill comprising a housing having .front and rear walls,Aa hollow shaft rotatably supported by said walls and having a flange atone end beyond and vadjacent said front wall, a ring die carried by saidflange, a door hinged to said housing and adapted to enclose said dieand engage the edge thereof to complete a die chamber, extrusion meanswithin said die chamber carried by said door and adapted for withdrawalwith opening of said door, and means for feeding extrudable materialthrough said hollow sha-ft into said die chamber for extrusion throughsaid die, said feed means including a feed screw lying within saidhollow shaft and extending beyond the other end thereof, and a feedscrew housing for the extended portion of said feed screw, said screwhousing including a feed hopper, and means for rotating said hollowshaft and said feed screw.

3. An extrusion mill comprising a housing having front and rear walls, ahollow shaft rotatably supported by said walls and having a flange atone end beyond and adjacent said front wall, a ring die carried by saidtiange, a chamber type door hinged to said housing and adapted toenclose said die to form an extruded product chamber thereabout and toengage the edge of said die to complete a die cha-mber, extrusion meanswithin said die chamber, means for feeding extrudable material throughsaid hollow shaft into said die chamber for extrusion through said die,and means for protecting the rotatable shaft supporting means of saidfront wall from material in said extruded product chamber, saidprotecting means including a blocking wall aixed to said flange andextending substantially to the inner peripheral wall surface of saidextrusion chamber, a rib along said inner peripheral wall surfaceadjacent said blocking wall, and a shroud on said blocking walloverhanging said rib.

4. An extrusion mill comprising a housing having front and rear walls, ahollow shaft rotatably supported by said walls and extending beyond saidfront wall, a ring die carried on an end `of said shaft beyond andadjacent said front wall, a door hinged to said housing and adapted toenclose said die and engage the edge thereof to complete a die chamber,extrusion means within said die chamber, said extrusion means includinga roll tixedly secured to a shaft extending through said door, bearinglmeans carried by said door externally of said die chamber for rotatablysup-porting said roll shaft, and means for feeding extrudable materialthrough said hollow shaft into said die chamber for extrusion throughsaid die.

5. An extrusion mill comprising a housing having front and rear walls; abearing assembly in said front wall; a bearing assembly in said rearwall in alignment with said first bearing assembly; a hollow shaftpassing through and supported by said bearing assemblies; said hollowshaft having a -ange at one end beyond and adjacent said front wall; aring `die carried by said flange; a chamber type door hinged to saidhousing and adapted to enclose said ring die and engage the edge of saiddie to complete a die chamber and at the same time form an extrudedproduct chamber about said die, said door having an external cylindricalflange on the front wall thereof and an insert in the front wall havingan opening concentric with said cylindrical flange and a dischargeopening at the lower .end of said door; extrusion means supported withinsaid cylindrical ange and extending through said door opening into saiddie chamber, said extrusion means including a sleeve iitting into saidcylindrical flange and removably secured therein, spaced bearings withinsaid sleeve, a shaft journalled in said bearings and extending into saiddie chamber, and an extrusion roll aixed to said shaft within said diechamber, said shaft having a flange adjacent said door; leak seal meansbetween the edge of said shaft ange and said sleeve and between saidShaft flange and said door insert; said door, at the lowermost point ofthe junction of said cylindrical ange and door insert, having a passagefor discharge of material esca-ping past said seals; and means forfeeding ext-rudable material into said die chamber, said means includinga feed screw lying within said hollow shaft and protruding beyond theback wall supported end of said hollow shaft, and a screw housing forthe extended portion of said feed screw.

6. A pellet mill comprising a cylindrical die, means rotatablysupporting said die at one end thereof, a clo- 20 23361114 sure for theopposite end of said die, an extrusion roll supporting shaft journalledin said closure with the roll supporting end of shaft terminating withinsaid die and the opposite end terminating in said closure, an extrusionPoll iixedly mounted on said shaft within said die and in extrusionengagement therewith, means for driving said die, and means foradjusting said extrusion roll with Irespect to the proximate surface ofsaid die, said adjusting means comprising a bearing housing on saidclosure, a bearing assembly in said bearing housing and including anangularly adjustable eccentric bushing and spaced roller bearingssurrounding the associated roll supporting shaft within said eccentricbushing, whereby angular rotation of said eccentric bushing will shiftslightly the included roll supporting shaft.

References Cited in the tile of this patent UNITED STATES PATENTS2,063,404 Selman Dec. 8, 1936 Meakin Dec. 7, 1943 2,798,444 Meakin July9, 1957

